Astronomical clock



May 3, 1966 A. F. SPlLHAUS ASTRONOMICAL CLOCK 7 Sheets-Sheet 1 Filed Dec. 10, 1965 FIG. I.

INVENTOR ATHELSTAN F. SPILHAUS BY Av w ATTORN YS y 3, 1966 A. F. SPILHAUS 3,248,866

ASTRONOMI CAL CLOCK Filed Dec- 10, 1963 7 Sheets-Sheet 2 INVENTOR \c/ m ATHELSTAN F. SPILHAUS ATTORNEY y 1966 A. F. SPILHAUS 3,248,866

ASTRONOMIGAL CLOCK Filed Dec. 10. 1963 7 Sheets-Sheet 5 SEPTEMBER ATTORNEYS May 3, 1966 A. F. SPILHAUS 3,248,866

ASTRONOMICAL CLOCK Filed Decl0 1963 7 Sheets-Sheet 4 l V 2 r 8 4 m, I I

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V/////////////////////////////////A INVENTOR y 1966 A. F. SPILHAUS 3,248,866

ASTRONOMI CAL CLOCK Filed Dec. 10, 1963 7 Sheets-Sheet 5 l4 le INVENTOR.

ATHELSTAN F. SPILHAUS kl zf r vb wai- ATTORNEYS y 3, 1966 A. F. SPILHAUS 3,248,866

ASTRONOMICAL CLOCK 7 Sheets-Sheet 7 Filed Dec. 10, 1963 INVENTOR.

ATHELSTAN E SPILHAUS BY ATTORNEYS United States Patent 3,248,866 ASTRONOMICAL CLOCK Athelstan F. Spilhaus, St. Paul, Minn. University of Minnesota Institute of Technology, Minneapolis 14, Minn.)

Filed Dec. 10, 1963, Ser. No. 329,433 2 Claims. (Cl. 58- -3) This invention relates to astronomical clocks and particularly to a clock which provides for the display of a great variety of astronomical data.

Clocks are known which display astronomical data in a more or less qualitative form and clocks are also known which display limited amounts of data quantitatively. The present invention relates particularly to a clock displaying a great variety of astronomical data to a sufficiently arcurate quantitative extent as to fit the desires of many persons interested in such data, among whom might be listed persons directly interested in astronomy, navigation, boating or fishing, seashore resident, etc. The clock provided in accordance with the invention may also be used for instruction purposes in many fields having to do with astronomy or its offshoots. While, usually, the clock would be set to follow accurately astronomical phenomena existing at a present time, for instruction purposes it may be adjusted arbitrarily to illustrate special occurrences and then reset to normal. The general object of the present invention is to provide such a clock which despite the great variety of data presented by it and quantitative accuracy is relatively simple in its construction, adjustment and operation.

Briefly stated, the clock comprises one set of five dials of which four are concentrically rotatable and closely superimposed so that relatively moving indicia thereon may be used for indications, the four face dials, at least, being transparent so that observation of the rearmost dial may be made, this rearmost dial being imprinted preferably with a dark background on which are indicated the major constellations and other data as will shortly appear. The fixed dial outlines the horizon and carries other markings of significance.

Among the matters exhibited by the set of dials just mentioned are the following:

The constellations and their component stars in their positions with respect to the horizon marked with compass points so that an observer may determine at the time given by the clock what stars will be visible and their positions with respect to compass points and their approximate declinations.

The position of the sun is also ascertainable with respect to the horizon and also the approximate times of sunrise and sunset.

Demonstrated also is the apparent progress of the sun through the constellations, and of course its relationship to the vernal equinox. Concurrent with this is the indication of the day of the year, so that the clock is also a calendar. Solar time is indicated by this set of dials.

. The position of the moon is also indicated in its relation to the stars and sun, as are also indicated its phases.

Indications are also given from which approximate times of moon rise and moon set may be determined.

Tides are indicated and settings are provided to enable the clock user to set the indications for local tide conditions. Times before and after high tides may be determined.

Various other data are exhibited as will become more apparent from consideration of matters set forth hereafter.

The clock further embodies a conventional clock driven in the case of electrical alternating current powering by a conventional synchronous clock motor which drives the other moving elements of the clock through proper gearing. The synchronous motor may be replaced by a spring or a battery powered clock mechanism if the clock is to be used under conditions, as on boats, in which the usual sixty cycle supply or other control frequency supply is not available. Additionally there -is provided a clock indicating time in various locations throughout the world, with Greenwich mean time of special interest.

The moving dials of the astronomical clock have a particularly advantageous construction and mounting. They are in the form of gears made of transparent plastic and by reason of their size they may have large numbers of teeth giving rise to simplification of gearing and high accuracy of relative motions. In particular, moon positions and times of tides are indicated with high accuracy over very long time periods. Further, shafts are eliminated by mounting the toothed dials in guides of Teflon or similar antifriction material providing for free movement without the necessity for any liquid lubrication. The absence of shafts avoids interference with display of indicia located at or near the center of the dials.

Adjustments are provided for initial settings of the displayed elements to take care of time settings, geographical locations, and initial date for moon positions and tides. These adjustments also provide for special settings for purposes of instruction.

The general objects of the invention indicated above and others relating to details of construction and operation will become more apparent from the following description, read in conjunction with the accompanying drawings in which:

FIGURE 1 is a perspective view showing the general appearance of the clock;

FIGURE 2 is an elevation of the toothed dial which will be referred to as the tide dial;

FIGURE 3 is an elevation showing the fixed dial which may be conveniently referred to as the horizon dial;

FIGURE 4 is an elevation of a toothed dial which will be referred to as the moon dial;

FIGURE 5 is an elevation of the toothed dial which will be referred to as the sun dial;

FIGURE 6 is an elevation of the toothed dial which will be referred to as the star dial;

FIGURE 7 is a vertical sectional view taken inside the front of the clock case illustrating both the visible elements and the elements of the drive gearing, the displayed data of the upper dials in this figure being only fragmentarily indicated;

FIGURE 8 is a sectional view through the case showing the mechanism partly in side elevation and partly in section;

FIGURE 9 is a fragmentary section taken on the plane indicated at 99 in FIGURE 7;

FIGURE 10 is a fragmentary section taken on the plane indicated at 10 10 in FIGURE 7;

FIGURE 11 is a fragmentary rear elevation showing primarily the controls for effecting adjustments; and

FIGURE 12 is an exploded perspective view illustrative of the drive and adjustment arrangements.

The clock comprises a case 2 which may be of any suitable decorative type, 'the case being provided with circular windows indicated at 4, 6 and 8 through which are displayed, respectively, the astronomical data, local time, and world time, the latter showing the local times at various places on the earth, and specifically Greenwich mean time. The numerals for the local time clock may be displayed on an annular ring at the periphery of the window 6.

A plate 10 hinged at its lower edge at 12 is arranged to be tilted rearwardly as indicated at 10 and is normally held in its upright closed position by spring latches (not shown). This plate carries all of the operating parts of the clock, and hinging is provided to make the sun disc accessible for adjustment.

The astronomical display of the clock is effected by the use of relatively movable discs respectively designated 14, 16, 18, 20 and 22 which are shown in FIGURES 2 to 6, inclusive. It will be convenient to describe these discs in the order from back to front of the clock. They are concentrically mounted in slightly spaced relationships and since all of the discs except the rearmost are transparent, the indicia of all are visible to the observer. All are desirably formed from a transparent plastic such as a methyl methacrylate resin (e.g., Plexiglas). The indicia may be printed thereon by silk screening.

Referring to FIGURE 6, the disc 14, the star disc, is in the form of a gear having teeth 24 which in the modification disclosed are 365 in number. The number of teeth given herein will be described to provide a consistent set to give the gear ratios for proper relative motions. One of the advantages of the present invention is that because of the use of large diameter discs for the astronomical set teeth may be provided on their peripheries in sufficient numbers to give, conveniently, the accurately desired gear ratios, this feature being coupled with the mountings of the discs at their peripheries and avoidance of the necessity for central nested shafts which would impair the display. The disc 14 except at its periphery provides a star chart on which the constellation and the principal visible stars are indicated at 26. The disc is concentric with the north celestial pole, Polaris being indicated at 27. For best display the star chart is provided with a dark background indicated at 28 (blue or black) which may have contrasting areas indicative of the extents of the constellations. On these the various indicia are printed in white or other light color. For clarity, of course, the imprinted constellations and stars are shown in the drawings in black. The star field may be quite detailed but is only indicated in part in FIGURE 6. Other indicia superimposed on the star field comprise the curve 30 which cooperates with sunrise and sunset scales on the sundial, declinations markings 36 and a sidereal time indicating arrow 38. Provided at the periphery of the disc 14 are the month markings 32 and the day markings 34, which for ease of reading may have fifth days accentuated. The month and day markings show desirably in black on a white opaque field so that the disc 14, as a whole, presents an opaque background. However, if back illumination is provided this disc may be translucent with transparent markings.

The next disc in front of that just described is the sun disc 16, FIGURE 5, which is provided with 366 teeth 40 about its periphery. The pitch of the teeth of the disc 14 and 16 is the same and then mesh with identical idler pinions rotating together as will appear hereafter. The sun disc is transparent except for the markings which may be in white or gold. (For consistency here and hereafter it will be assumed that the clock is to be illuminated from its front; variations for back illumination will be obvious.) For easy recognition the sun is indicated by the disc 42 through which passes the radial line 44. The intersection of this line across the horizon shows the approximate azimuth of the sun, though for casual observation the sun disc 48 may be used. This disc carries the sunrise and sunset scales 46 and 48 (to be read with respect to the curve 30), and also moon phase indicia 50, 52, 54 and 56 which may be used in estimation of the appearance of the moon.

The next disc in sequence from the back to the front is disc 18, FIGURE 4, which is provided with 443 teeth 58. Using this number of teeth and a somewhat smaller tooth size than for the teeth of the two discs already described the disc 18 may be of comparable diameter so as to be similarly mounted at its periphery. For example, typically, the star and sun discs may have teeth of 40 pitch while the moon and tide discs may have teeth of 48 pitch. The moon disc carries a representation 60 of the moon and a radial line 62 therethrough, both desirably printed in white.

The line 62 is particularly useful in approximately identifying the azimuthal position of the moon by its intersection with the horizon 64. This line read against the numerical hour markings 65 along the horizon also gives .an approximate time interval from which moon rise or moon set may be estimated relative to its meridian position.

In front of the moon disc there is the fixed disc 20, FIGURE 3. Its major markings 64, is of the horizon which is marked with the compass points as shown at 66. Solar times are indicated at 68 and against these may be read the sun line 44 and for sidereal time the arrow 38. The horizon marking is for a particular latitude in which the clock is expected to be used, but different horizons may be provided for the various latitudes. Hour markings 65 running from south eastwardly and westwardly along the horizon are of use in estimating times before or after high tide, times of moon rise and moon set, etc. The markings on disc 20 may be in white, the remainder of the disc being transparent.

The front disc 22, FIGURE 2 is the tide disc and is dimensionally the same as the moon disc 18, there being 443 teeth at 72. Tide markings are provided as shown at 73 and 74 indicative of high, low and intermediate tide conditions. These markings may be in white, the remainder of the disc being transparent. The markings read against the horizon indicate the tide conditions: i.e. when one of these markings is at the top of the horizon, high tide exists; and the deviation along the horizon indicates time before or after high tide. The scales 73 and 74 themselves indicate the tide condition when read against the horizon line. A tide disc separate from the moon disc is provided to permit adjustments to be made indicative of local tide conditions.

All of the discs 14, 16, 18, 20 and 22 are mounted concentrically by Teflon guides 76, 78, 88 and 82, secured to the plate 10 and slotted to receive the peripheries of the discs. The rotating discs are thus mounted for free, lowfriction movement and the guides serve to maintain the teeth of these discs in mesh with their driving gearing. In the case of the stationary horizon disc 20, rotation is prevented by ears 84 of this disc embracing the sides of the uppermost Teflon guide 76. In the case of the sun disc 16 play in the guides is desirably sufficient so that this disc may be moved out of mesh with its driving idler and so initially adjusted to bring its indications of time and the indications of the local time clock in proper relationship. For example, during daylight saving time the time indicated by the sun disc should be standard local time while it will generally be desirable to have daylight saving time indicated by the clock. Because changes in this respect would normally be made only twice a year it is not worth involving independent setting means since the sun disc may be readily lifted, adjusted, and then dropped into mesh, meshing being thereafter maintained merely by the weight of the disc.

The plate 10 mounts the driving clockwork 86. When the clock is to be used with a controlled frequency alternating current source, the clockwork is desirably of the synchronous motor type incorporating reduction gearing to provide drive for the conventional hour, minute and sweep second shafts-88, 90 and 92, respectively. However, the clockwork may be of wound spring type or of the type maintained in operation by direct current. The conventional time-setting adjustment is provided at 87 and, as will become apparent, this serves not only for the adjustment of the hour and minute hands of the clock but also for the other elements which are driven by the hour shaft 88. The hour, minute and sweep second hands are illustrated in FIGURE 7 at 94, 96 and 98 and are readable against the twelve hour dial 99 which is in the form of a concentric marked ring carried by the frame.

The hour shaft 88 has secured to it a composite gear comprising two gears 100 and 102. The former, at the rear, has 183 teeth, while the latter 102 has 214. If, for

example, the former are forty pitch, and the latter fortyeight pitch, the two gears are approximately of the same diameter.

The gear 100 drives a 45 tooth idler 104. A pair of coaxial idlers 106 and 108, each having 45 teeth, are driven together by the idler 104 which meshes with the idler 106. Provision, later described, is made for relative adjustment of the idlers 106 and 108. These idlers respectively drive the sun disc 16 having 366 teeth and the star disc 14 having 365 teeth. Because the pitch diameters of the last'mentioned discs are very nearly the same, proper driving conditions are achieved even though these discs are essentially coaxial, very slight backlash taking care of proper driving conditions.

A pair of pinions 110 and 112 are coaxially mounted for simultaneous drive, though provision is made as will appear later for relative adjustment of these pinions. The former is provided with 54 teeth meshing with the 214 teeth of the gear 102. The latter is provided with 27 teeth.

Three pinions 114, 116 and 118, each having 54 teeth, are mounted coaxially'but are relatively adjustable as will later appear. The pinion 110 meshes with the pinion 116 and this serves for the drive of the pinions 114 and 118 which mesh, respectively, with the teeth of the discs 22 and 18, each of which discs is provided with 443 teeth as mentioned previously.

The pinion 112 meshes with the teeth 122 of a disc 120 of transparent plastic of the same type as that used for the discs previously described. There are 214 teeth 122. The disc 120 is mounted in slotted Teflon guides 124, 126 and 128 to provide for free, low-friction movement. Imprinted on the discs 120 are twenty-four hour indications 130 with associated radial lines 132 for easy reading against a world map imprinted as indicated at 134 desirably with outlines of the continents, major cities, and other markings indicative of the longitude of Greenwich and the international date line. These latter matters 134 are printed on a plate 136 which is secured to the plate 10 behindthe disc 120, the plate 136 serving for the mounting of the Teflon guides.

The matter of the adjustments will now be described.

The adjustment of the star disc relative to the sun disc is provided by the mounting of pinions 106 and 108 by means of a bearing 138 carrying at its ends Teflon washers 139 providing for low friction mounting of a tubular shaft 140 to which is secured an adjusting knob 141. Ascrew 142 is threaded into the forward end of the shaft 140 and bears on a disc-type spring 144 to clamp together the pinion 108 which is secured to the shaft 140 by a press fit, the pinion 106 which has a running fit on the shaft, and interposed washers which may be of nylon to provide frictional driving engagement between the pinions while permitting the pinion 108 to be adjusted, the pinion 106 being driven by the pinion 104 as already described.

In the case of the moon and tide discs, these must both be adjustable independently of their drive. As already described, there are three equal size pinions 114, 116 and 118, the first driving the tide disc, the last themoon disc, and the intermediate one being driven from the pinion 110. A bearing 146 provided, as previously described, with Teflon bearing washers, mounts the sleeve 148 within which there is in turn mounted the shaft 152. The sleeve 148 carried the knob 150 and the shaft 152 carries the knob 154. A spring 156 is located between these knobs and provides adjustable clamping action between the pinions which are separated by washers, the pinion 118 being secured by a press fit to the sleeve 148 while the pinion 114 is secured by a press fit to the shaft 152. The pinion 116, driven by the pinion 110 will carry frictionally with it during driving the pinions 114 and .118, but these may be individually adjusted relative to it ing 157 provided with Teflon washers as previously mentioned which mount a shaft 158 to which there is secured the adjusting knob 160. The pinion 112 is secured to this shaft and an interposed spring 162 provides clamping to the pinion 110 which is driven by the gear 102. This arrangement, accordingly, provides normal frictional drive of the world time clock disc, but this may be adjusted by manipulation of the knob 160.

The descriptions so far given will have made generally clear the operation of the clock. The drive of the local time clock is, of course, straightforward from the clockwork, and the drive of the world time clock disc through one revolution in twenty-four hours is through the gearing 102, 110, 112 and 122, the last being provided by the teeth on the disc 120;

Adjustment of the clockwork simultaneously adjusts the hands of the local time clock and the disc 120, but the latter may be independently adjusted by the knob 160. This last adjustment takes care of the difference between standard and daylight saving time, and also the matter of settings for different localities, so that Greenwich mean time may be read on the world time clock.

The drives of the star and sun discs from the equal 1 size pinions 106 and 108 and the arrangement of the 365 teeth on the star disc and the 366 teeth on the sun disc take care of the proper exhibiting of the suns apparent motion through the stars. The setting of the stars relative to the sun is taken care of by adjustment of the knob 141. Plroper adjustment of the day indication is also thus afiorded to take care of leap year correction. (The qularter day per year change is so slight in affecting observation as not to warrant special gearing, and a one day shift adequately takes care of the leap year change.)

Adjustments relative to the horizon are simultaneously made. Sunrise and sunset indications are provided by reading the scales 46 and 48 against the curve 30 provided for this purpose.

The motion of the moon is very accurately reproduced (to approximately one part in ten thousand) by the gearing descmibed. The phases of the moon are indicated by reading its position relative to the markings 50, 52, 54 and 56 on the sun disc. Estimates of times of moon rise and moon set are made by reference to the hour markings along the horizon.

Tide conditions are readable from the tide discs. The setting of the tide disc is to take care of local or other tides of interest and settings may be made with reference to suitable tide tables. Once set, however, the tides are indicated with good accuracy.

More or less astronomical indications may be provided as desired. For example, the ecliptic and equator may be indicated. Mechanical variations may also be made. For example by incorporating in the driving gearing for the sun disc friction adjustment means of the type already described the sun disc may be adjusted independently of the hands of the local time clock.

It will be evident that various other details may be changed without departing from the invention as defined in the following claims.

What is claimed is:

1. An astronomical display clock comprising a plurality of approximately coextensive rotatable discs each of which is toothed at its periphery to form a gear, a first of said discs displaying indicia representing the celestial sphere, a second of said discs displaying indicia indicative of the position of the sun, and a third of said discs displaying indicia indicative of the position of the moon, means mounting said discs coaxially, a stationary reference member displaying indicia indicative of an o bservers horizon, the last mentioned member and said discs being stacked adjacent to each other with all of said discs in front of the rrearm'ost being primarily transparent except for the indicia thereon so that the superimposed indicia may be viewed simultaneously, and a clockwork mechanism driving said respective first and second discs in the same direction in the speed ratio of 366/365 with the latter at the rate of one revolution per day and driving the third disc in said direction in the speed ratio of 428/443 with respect to said second disc, the number of teeth on said third disc being greater than the number of teeth on either of said first and second discs, and the pitch of said teeth on said third disc being greater than the pitch of the teeth on said first and second discs.

2. An astronomical display clock comprising a plurality of approximately coextensive rotatable discs each of which is toothed at its periphery to form a gear, a first of said discs displaying indicia representing the celestial sphere, a second of said discs displaying indica indicative of the position of the sun, and a third of said discs displaying indiccia indicative of the stage of a tide when read against indicia indicative of an observers horizon, means mounting said discs co axially, a stationary reference member displaying indicia indicative of an observers horizon, the last mentioned member and said discs being stacked adjacent to each other with all of said discs in front of the 'rearmost being primarily transparent except for the indicia thereon so that the superimposed indicia may be viewed simultaneously, and a clockwork mechanism driving said respective first and second discs in the same direction in the speed ratio of 366/365 with the latter at the rate of one revolution per day and driving the 8 third disc in said direction in the speed ratio of 428/443 with respect to said second disc, the number of teeth on said third disc being greater than the number of teeth on either of said first and second discs, and the pitch of said teeth on said third disc being greater than the pitch of the teeth on said first and second discs.

References Cited by the Examiner UNITED STATES PATENTS 1,768,100 6/1930 Ba-umgarten 58-126 2,248,195 7/1941 Prins 58-425 2,400,099 5/ 1946 Brubaker et al. 2,466,312 4/1949 Heintz 58-425 2,749,704 6/1956 Heikkila 58126 2,803,300 8/1957 Warkentien 5885.5 X 2,828,649 4/1958 Boerdijk et a1. 5826 X 2,852,908 9/1958 Stern et a1. 58-126 X 2,892,304 6/1959 Eaves 5885.5 3,032,377 5/1962 Blase 308-3 FOREIGN PATENTS 480,518 2/1938 Great Britain.

LEO SMILOW, Primary Examiner.

G. F. BAKER, Assistant Examiner. 

1. AN ASTRONOMICAL DISPLAY CLOCK COMPRISING A PLURALITY OF APPROXIMATELY COEXTENSIVE ROTATABLE DISCS EACH OF WHICH IS TOOTHED AT ITS PERIPHERY TO FORM A GEAR, A FIRST OF SAID DISCS DISPLAYING INDICIA REPRESENTING THE CELESTIAL SPHERE, A SECOND OF SAID DISCS DISPLAYING INDICIA INDICATIVE OF THE POSITION OF THE SUN, AND A THIRD OF SAID DISCS DISPLAYING INDICIA INDICATIVE OF THE POSITION OF THE MOON, MEANS MOUNTING SAID DISCS COAXIALLY, A STATIONARY REFERENCE MEMBER DISPLAYING INDICIA INDICATIVE OR AN OBSERVER''S HORIZON, THE LAST MENTIONED MEMBER AND SAID DISCS BEING STACKED ADJACENT TO EACH OTHER WITH ALL OF SAID DISCS IN FRONT OF THE REARMOST BEING PRIMARILY TRANSPARENT EXCEPT FOR THE INDICIA THEREON SO THAT THE SUPERIMPOSED INDICIA MAY BE VIEWED SIMULTANEOUSLY, AND A CLOCKWORK MECHANISM DRIVING SAID RESPECTIVE FIRST AND SECOND DISCS IN THE SAME DIRECTION IN THE SPEED RATIO OF 366/365 WITH THE LATTER AT THE RATE OF ONE REVOLUTION PER DAY AND DRIVING THE THIRD DISC IN SAID DIRECTION IN THE SPEED RATIO OF 428/443 WITH RESPECT TO SAID SECOND DISC, THE NUMBER OF TEETH ON SAID THIRD DISC BEING GREATER THAN THE NUMBER OF TEETH ON EITHER OF SAID FIRST AND SECOND DISCS, AND THE PITCH OF SAID TEETH ON SAID THIRD DISC BEING GREATER THAN THE PITCH OF THE TEETH ON SAID FIRST AND SECOND DISCS. 